Full name of site: Taq-I-Kisra
(Arch of Ctesiphon)Country: Iraq
Short description of site (also include multiple locations if applicable): this is the only remaining structure left in what was for seven centuries the capital of the Seleucid, Parthian and Sassanid empires of Persia. Built in 400 A.D. it is the largest brick built arch in the world
Criteria (Cultural): i.Despite being built nearly 16 centuries ago this is still the largest brick built arch in the world, it is of unparalleled Architectural genius.
ii.This is an excellent illustration of the development of architecture in the region
iii.The Palace at Ctesiphon was a capital of successive dynasties for seven centuries that controlled Mesopotamia.
iv.Is an outstanding example of a palace structure from the 5th-13th centuries
Outstanding universal value / comparative analysis:The arch is a remarkable survivor from this period of Mesopotamian history and is a great testament to successive Persian dynasties.
Architecturally there are a few comparable sites. In terms of the size and age of the arch it would be similar to the Pantheon in Rome, Hagia Sofia in Istanbul or Soltaniyeh.
I am racking my brains but can not think of a palace structure of similar age that would be inscribed on the list, they are either earlier ruins (Persepolis and Pasergadae) or later examples throughout Europe and Asia.
The site is on the Global Heritage Funds critically endangered list and is in pretty dire need of protection. One for the list of sites in danger if it is approved.